The objective of our research is to discover how the various components of the sensory trigeminal complex operate in the mediation of oro-facial pain. To this end, we have been carrying out two concurrent programs of research. The first utilizes electrophysiological procedures to study the responses of pontine and bulbar neurons to noxious and innocuous peripheral stimuli. Acute experiments are performed upon lightly anesthetized, immobilized cats and monkeys. The second program makes use of monkeys with surgically implanted dental stimulating electrodes. The awake, unanesthetized animals are studied in an operant (escape) paradigm while behavioral responses to graded electrical tooth stimulation are recorded. After consistent response patterns are established, the animals are studied in acute, electrophysiological experiments, as above. Ultimately, behavioral, physiological and anatomical data are analyzed and inter-related.